The manufacturing process for microcircuits or semiconductor integrated circuits of liquid crystal display devices comprises several steps of: forming a variety of lower films such as a conductive metal film that is made of aluminum, an aluminum alloy, copper, a copper alloy, molybdenum, or a molybdenum alloy, or an insulating film such as silicon oxide film, a silicon nitride film, or an acryl insulating film on a substrate; uniformly coating a photoresist on such a lower film; optionally exposing and developing the coated photoresist to form a photoresist pattern; and patterning the lower film with the photoresist pattern as a mask.
After these patterning steps, a process of removing the photoresists remaining on the lower film is undergone. For this purpose, a stripper composition for removing the photoresists is used.
Previously, stripper compositions including amine compounds, polar protic solvents and polar aprotic solvents, and the like have been well known. Among them, stripper compositions including N-methyl formamide (NMF) as the polar aprotic solvent have been widely used.
These stripper compositions including NMF are known to exhibit excellent stripping ability of the photoresists. However, such NMF is a Category 1B (GHS Standard) material showing a reproductive toxicity and its use is being gradually restricted.
On this account, various attempts have been made to develop stripper compositions showing excellent stripping and rinsing abilities without using NMF, but such stripper compositions showing sufficient stripping and rinsing abilities have not been properly developed so far.
Moreover, conventional stripper compositions including the NMF promote decomposition of the amine compounds with the passage of time and so there were problems in that the stripping and rinsing abilities are lowered with the passage of time.
In particular, these problems can further accelerate when a part of the remaining photoresist is dissolved in the stripper composition, depending on the application times of the stripper composition.
In view of these circumstances, in order to maintain excellent stripping and rinsing abilities with the passage of time, a method for incorporating an excess amount of amine compounds in the stripper composition has been adopted in the prior art. However, in this case, the economy and efficiency of the process may be greatly reduced, and there may incur environmental and procedural problems due to the incorporation of the excess amount of amine compounds.
Thus, there is a need to develop a new stripper composition which is capable of maintaining excellent stripping and rinsing abilities with the passage of time while not including a solvent showing a reproductive toxicity.